Taylor Model 70A multimeter - UK Vintage Radio Repair and Restoration Discussion Forum

TonyDuell · 14th Jun 2018, 12:11 pm

Can anybody tell me anything about the Taylor Model 70A multimeter. It claims to be 1000 Ohms/volt, so I guess it was a sort-of competitor to the AVO model 7. Looks to be quite old, in a metal case. I bought one this morning, not that I NEED another multimeter...

There's a removable plate on the back to cover the battery compartment, which seems to have been designed for a grid bias battery based on the size and the fact that there are 3 leads terminating in wander plugs. The case is somewhat rusty, but the insides look fine and the meter movement still works.

Does anyone have a circuit diagram for it?

factory · 14th Jun 2018, 10:02 pm

I think I have a manual for the Taylor Model 70A Universal Meter Series 1 somewhere, it probably has the circuit diagram but Taylor didn't always provide the component values.

It's 1000 ohms per volt on both AC & DC ranges and uses a 1mA full scale Model 400 meter movement.

David

karesz* · 14th Jun 2018, 11:52 pm

Taylor companys history in short:
Founded in 1947, in 1958 took over AVO, AVO Ltd was acquired from Metal Industries Ltd in 1957 and in 1967 Thorn Electrical Industries took over Metal Industries...
Regards, Karl

TonyDuell · 15th Jun 2018, 5:09 am

That looks like the one I have. My case is also rusty in places, but the internals look very clean. Mine works, at least on the DC voltage and current ranges (tested with a couple of dry cells and resistors, so no way a check on calibration, but it gives sensible readings and the pointer doesn't stick).

The plate on the back (in the second photo) comes off with the obvious 6 screws to reveal a compartment with 3 wires ending in wander plugs. I assume this is a battery compartment for the ohms ranges and that it took one of those multi-tapped grid bias batteries.

'Factory', if you find the manual, I would be very interested in seeing a scan of it (or of the useful pages).

factory · 15th Jun 2018, 9:24 pm

It does use a grid battery for the ohms ranges, the manual gives the following connections for the wander plugs;

Red +
Green -1½V
Black -9V

Here are a couple of pictures, one of the battery connections and the other the circuit diagram (no component values, as suspected).

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I'm busy this weekend, but will try to get the manual scanned sometime in the next week.

David

TonyDuell · 16th Jun 2018, 5:23 am

Thanks for that information. I will make up some replacement for the battery and see if I can get it working fully...

With the Ohms ranges powered by 1.5V and 9V, it really does look like a competitor to the AVO 7

factory · 22nd Jun 2018, 9:52 pm

I've scanned the manual and used MS Word & Foxit to convert it to a pdf (attached below), if anyone would like a higher resolution version of the pdf (18Mb) I can email it (send me a PM).

David

TonyDuell · 23rd Jun 2018, 4:40 am

Thanks for that manual. I am sure I can get the instrument working now (as the meter movement is certainly good). I just need to make up a battery for the ohms ranges.

pmmunro · 24th Jun 2018, 4:25 pm

Quote:

Originally Posted by karesz*

Taylor companys history in short:
Founded in 1947, in 1958 took over AVO, AVO Ltd was acquired from Metal Industries Ltd in 1957 and in 1967 Thorn Electrical Industries took over Metal Industries...
Regards, Karl

The takeovers were the other way round. Avo acquired Taylor shortly before Avo became part of the Metal Industries Group.

I don't have a founding date for Taylor, but it was before 1947. Taylor brought a case challenging an ACWEECO (later AVO) patent in 1943.

PMM

WME_bill · 24th Jun 2018, 7:00 pm

Following PMM's comments about Avo.
I always understood that Avo took over Taylor Instruments of Slough in 1958 to acquire the Taylor patents to the centre pole meter movement, which permitted a more robust movement and much greater sensitivity.

Older history:
Donald McAdie had started the Automatic Coil Winder and Electrical Equipment Company in 1923 to make his coil winding machine which could wind a specific length of wire, and used it to make the DC Avo meter in 1923, with those neat bobbins of resistance wire for each range resistor.
Hugh S McAdie invented the Avo AC/DC multimeters in 1933.

Donald died in 1955, so that might have been the spur to make Avo a public company in 1957.
The Avo + Taylor business was taken over in 1959 by Metal Industries, a mini-conglomerate, at a time when these things were fashionable. It was primarily a metal dealer and ship-breaker who happened to own Brookhurst Igranic Switchgear.
They then bought Lancashire Dynamo, doubling in size.

The original Avo factory was in Vauxhall Bridge Road. It was moved to Dover in 1962.
Hugh S McAdie retired in 1966, and died in 1969. This might have been the trigger for Thorn to bid for the whole group in 1967 after a fiercely fought takeover battle with Aberdaire Holdings controlled by Slater Walker.

Thorn had previously acquired Evershed and Vignoles, the Megger owners from George Kent Instruments in 1965. All merged at Dover.
Whole lot bought out by management in 1987 with the collapse of Thorn. Now renamed Megger Instruments.
wme_bill

factory · 24th Jun 2018, 8:20 pm

The oldest patent I can find for Taylor Electrical Instruments of Slough is for switches (application date 1943). They must go back further than that as I've seen London as the address on a Model 40 valve tester.

https://worldwide.espacenet.com/publ...&locale=en_EP#

David

ms660 · 24th Jun 2018, 8:23 pm

1939 in W.W.

Lawrence.

ex 2 Base · 24th Jun 2018, 8:36 pm

WME bill, you have just brought back some memories. Back in 1950/60 I was electrician on the railways, we had a lot of control gear, switchgear by Brookhurst Igranic, motors by Lancashire Dynamoes & Crypton,Mathers & Platt, Reyrolle switch gear, real quality. Sorry to deviate but could resist, Avo 7 was the meter of the day for us and S&T. Ted

14th Jun 2018, 12:11 pm	#1
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Taylor Model 70A multimeter Can anybody tell me anything about the Taylor Model 70A multimeter. It claims to be 1000 Ohms/volt, so I guess it was a sort-of competitor to the AVO model 7. Looks to be quite old, in a metal case. I bought one this morning, not that I NEED another multimeter... There's a removable plate on the back to cover the battery compartment, which seems to have been designed for a grid bias battery based on the size and the fact that there are 3 leads terminating in wander plugs. The case is somewhat rusty, but the insides look fine and the meter movement still works. Does anyone have a circuit diagram for it?

14th Jun 2018, 10:02 pm	#2
factory Octode Join Date: Jul 2009 Location: Cheshire, UK. Posts: 1,733	Re: Taylor Model 70A multimeter I think I have a manual for the Taylor Model 70A Universal Meter Series 1 somewhere, it probably has the circuit diagram but Taylor didn't always provide the component values. It's 1000 ohms per volt on both AC & DC ranges and uses a 1mA full scale Model 400 meter movement. David

14th Jun 2018, 11:52 pm	#3
karesz* Heptode Join Date: Jun 2010 Location: Zurich, Switzerland Posts: 538	Re: Taylor Model 70A multimeter Taylor companys history in short: Founded in 1947, in 1958 took over AVO, AVO Ltd was acquired from Metal Industries Ltd in 1957 and in 1967 Thorn Electrical Industries took over Metal Industries... Regards, Karl Attached Thumbnails

15th Jun 2018, 5:09 am	#4
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Taylor Model 70A multimeter That looks like the one I have. My case is also rusty in places, but the internals look very clean. Mine works, at least on the DC voltage and current ranges (tested with a couple of dry cells and resistors, so no way a check on calibration, but it gives sensible readings and the pointer doesn't stick). The plate on the back (in the second photo) comes off with the obvious 6 screws to reveal a compartment with 3 wires ending in wander plugs. I assume this is a battery compartment for the ohms ranges and that it took one of those multi-tapped grid bias batteries. 'Factory', if you find the manual, I would be very interested in seeing a scan of it (or of the useful pages).

15th Jun 2018, 9:24 pm	#5
factory Octode Join Date: Jul 2009 Location: Cheshire, UK. Posts: 1,733	Re: Taylor Model 70A multimeter It does use a grid battery for the ohms ranges, the manual gives the following connections for the wander plugs; Red + Green -1½V Black -9V Here are a couple of pictures, one of the battery connections and the other the circuit diagram (no component values, as suspected). I'm busy this weekend, but will try to get the manual scanned sometime in the next week. David

16th Jun 2018, 5:23 am	#6
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Taylor Model 70A multimeter Thanks for that information. I will make up some replacement for the battery and see if I can get it working fully... With the Ohms ranges powered by 1.5V and 9V, it really does look like a competitor to the AVO 7

23rd Jun 2018, 4:40 am	#8
TonyDuell Dekatron Join Date: Jun 2015 Location: Biggin Hill, London, UK. Posts: 5,208	Re: Taylor Model 70A multimeter Thanks for that manual. I am sure I can get the instrument working now (as the meter movement is certainly good). I just need to make up a battery for the ohms ranges.

24th Jun 2018, 7:00 pm	#10
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: Taylor Model 70A multimeter Following PMM's comments about Avo. I always understood that Avo took over Taylor Instruments of Slough in 1958 to acquire the Taylor patents to the centre pole meter movement, which permitted a more robust movement and much greater sensitivity. Older history: Donald McAdie had started the Automatic Coil Winder and Electrical Equipment Company in 1923 to make his coil winding machine which could wind a specific length of wire, and used it to make the DC Avo meter in 1923, with those neat bobbins of resistance wire for each range resistor. Hugh S McAdie invented the Avo AC/DC multimeters in 1933. Donald died in 1955, so that might have been the spur to make Avo a public company in 1957. The Avo + Taylor business was taken over in 1959 by Metal Industries, a mini-conglomerate, at a time when these things were fashionable. It was primarily a metal dealer and ship-breaker who happened to own Brookhurst Igranic Switchgear. They then bought Lancashire Dynamo, doubling in size. The original Avo factory was in Vauxhall Bridge Road. It was moved to Dover in 1962. Hugh S McAdie retired in 1966, and died in 1969. This might have been the trigger for Thorn to bid for the whole group in 1967 after a fiercely fought takeover battle with Aberdaire Holdings controlled by Slater Walker. Thorn had previously acquired Evershed and Vignoles, the Megger owners from George Kent Instruments in 1965. All merged at Dover. Whole lot bought out by management in 1987 with the collapse of Thorn. Now renamed Megger Instruments. wme_bill

24th Jun 2018, 8:20 pm	#11
factory Octode Join Date: Jul 2009 Location: Cheshire, UK. Posts: 1,733	Re: Taylor Model 70A multimeter The oldest patent I can find for Taylor Electrical Instruments of Slough is for switches (application date 1943). They must go back further than that as I've seen London as the address on a Model 40 valve tester. https://worldwide.espacenet.com/publ...&locale=en_EP# David Last edited by factory; 24th Jun 2018 at 8:26 pm. Reason: extra info

24th Jun 2018, 8:23 pm	#12
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Taylor Model 70A multimeter 1939 in W.W. Lawrence.

24th Jun 2018, 8:36 pm	#13
ex 2 Base Heptode Join Date: Nov 2009 Location: Scarborough, North Yorkshire, UK. Posts: 510	Re: Taylor Model 70A multimeter WME bill, you have just brought back some memories. Back in 1950/60 I was electrician on the railways, we had a lot of control gear, switchgear by Brookhurst Igranic, motors by Lancashire Dynamoes & Crypton,Mathers & Platt, Reyrolle switch gear, real quality. Sorry to deviate but could resist, Avo 7 was the meter of the day for us and S&T. Ted